Sen. Rand Paul is blocking quick action on a number of tax treaties, including with Switzerland, citing concerns about the privacy rights of Americans with foreign bank accounts.

"To be clear, I certainly do not condone tax cheats, but I can't support a law that endangers regular foreign investment and punishes every American in pursuit of a few tax cheats. Most importantly I cannot support a bulk collection tax treaty that has complete disregard for the important protections provided to every American by the Fourth Amendment," the Kentucky Republican wrote in a letter sent today to Senate Majority Leader Harry Reid, D-Nev.

Paul announced formally that he would object to any unanimous consent request or other expedited consideration of consenting to ratification of several tax treaties, which the Foreign Relations panel backed on April 1.

The Constitution requires a two-thirds majority of those present and voting for adoption of resolutions of ratification. When the Senate consents to noncontroversial treaties, it is customary to see Reid or his designee go through an odd sequence of standing up and sitting down to demonstrate the needed majority is present.

It's clear that will not happen in this case, given Paul's objection.

"Previous tax treaties were more focused on information specific to suspicions of tax fraud while requiring that serious allegations of tax wrongdoing were grounded in evidence," Paul wrote. "However, these new bulk collection treaties demand Americans' records under a vague standard that allows the government to access personal financial information that 'may be relevant' through information exchanges between the U.S. and foreign governments — a standard extended to other governments, as well."

Treaties with Switzerland and Luxembourg are included on the list, requiring an increase in the amount of information exchanged between the countries and the United States. Other agreements involve Chile, Hungary, as well as the the Council of Europe and the Organization for Economic Cooperation and Development.

Foreign Relations Chairman Robert Menendez, D-N.J., said during his panel's consideration of the tax treaties that they were “a crucial component of U.S. trade and tax policy."